Device for treating waste gases resulting from technical combustion processes

ABSTRACT

The invention relates to a device for treating exhaust gases, which can be arranged in the exhaust-gas stream from an internal combustion engine or in the exhaust-gas line from stationary combustion installations and which has a feed-line connection stub and a discharge-line connection stub. Feed-line connection stub ( 3 ) and discharge-line connection stub ( 4 ) are held on the housing ( 6 ) which contains a filter material which has at least one fabric layer made from metal wires or metal fibers. For diversion, for retention of particulates from the in the incoming exhaust-gas stream ( 1 ) and for muffling in the exhaust-gas stream and for purification of exhaust gases, in the housing ( 6 ) there are shaped bodies ( 8 ) which consist of metallic materials ( 19.1, 19.2 ) as composite material ( 19 ), the empty spaces ( 11, 16, 17 ) which are present in the housing ( 6 ) being filled with metallic fiber material.

The invention relates to a device for treating exhaust gases which areformed in industrial and technical combustion processes, for exampleexhaust gases from internal combustion engines, exhaust gases fromincineration operations or other industrial applications.

EP 0 505 832 B1 relates to a filter or catalyst support. It proposes afilter or catalytic converter body for eliminating harmful constituentsfrom the exhaust gases from an internal combustion engine, in particulara diesel engine. This includes at least one fabric layer comprisingmetal wires or metal fibers, sinterable material in powder, grain, fiberfragment or chip form being introduced into the meshes and sintered ontothe wires or fibers. The fabric is formed as a three-dimensional wirefabric, in the meshes of which sinterable material is introduced andsintered to the wires or fibers.

DE 37 31 766 C2 discloses a particle filter. The particle filter isarranged in the exhaust-gas stream from an internal combustion engine,in particular an air-compressing internal combustion engine, andincludes a housing which has a feed-line connection stub and adischarge-line connection stub for the exhaust-gas stream and in whichthere is arranged a filter material which includes knitted fibers andmineral filaments or yarns and is in multilayer form. The filter isformed at least in part or completely by a knitted fabric which has beencircular-knitted from the mineral filaments or yarns.

EP 0 446 422 A1 has disclosed a particle filter for an air-compressorinternal combustion engine. This document proposes a particle filter fordiesel engines having an inlet for the introduction of exhaust gases, anoutlet and a filter zone which lies between inlet and outlet andincludes a multiplicity of tubular, porous ceramic filter candles orfilter cylinders, the exhaust gas entering radially through thecylindrical walls of these filter candles or filter cylinders and theexhaust gas emerging again in the axial direction through the axialinterior space of these filter candles or filter cylinders. The porousceramic filter candles or filter cylinders are mounted elastically andsealed in the axial direction by means of a disk and in the radialdirection by means of a sleeve made from knitted, braided or woven metalfabric at their ends.

Finally, EP 0 437 685 B1 has disclosed a particle filter. The particlefilter for separating particulates out of the exhaust gases from aninternal combustion engine has a temperature-stable, porous metallicfilter body made from a metallic material with intermetallic phases ofNi, Al or Ni₃Al, the filter body of the particle filter being producedby sintering. The filter body comprises a braided wire fabric, metals ormetal compounds being admixed with the material in order to improve thesintering properties.

In previous systems for treating exhaust gases in the automotive sector,for example in exhaust muffling, the reflection principle has been used,in which muffling is brought about in the exhaust, whether this be inthe front muffler or in the main muffler, as a result of the exhaust-gasstream being diverted and broken up by means of a multichamber system.With the absorption principle, the muffling is effected by means offillers made from a very wide range of materials. In general, thediversion of the exhaust-gas streams in a muffler system is effected byperforated metal sheets in a very wide range of forms, whether as tubesor as stamped parts. A relatively rigid inner structure of the exhaustmuffler is produced from the abovementioned components by folding,welding or some other joining or connecting step. The empty spaces whichresult after the internal structure comprising stamped parts and tubeshas been put inside a casing are filled with a very wide range of fillermaterials, whether mineral wool (basalt) or glass wool. Stainless steelwool is used, for example, as a heat distributor and heat protection forthe other fillers, first high sound frequencies of the incomingexhaust-gas stream being broken up by the stainless steel wool.

The absorption principle, which has mainly been followed by previousmuffler structures, has the associated drawback that, on account of theperforation or stamping of the parts which form the internal structureof the muffler, it is very material-consuming and expensive, since avery wide range of expensive tools are required to stamp, perforate,drill and weld and the quantity of waste is not inconsiderable. The sameis also true with regard to the construction of catalytic converters forpurifying exhaust-gas streams from internal combustion engines. Shapingthe perforated metal sheets according to individual muffler designsrequires a type-specific configuration of the components and isassociated with a high level of outlay and considerable cost caused bysizing, stamping and stock-holding. Furthermore, the production of acomposite structure which is incorporated in skeleton form in thehousing of a muffler, whether this be a main muffler or a front muffler,is extremely labor-intensitive, and furthermore the construction whichemerges has a high intrinsic weight. By contrast, in the automotivesector the trend is toward ever more lightweight structures. The emptyspaces in a muffler provided with a skeleton-like structure are nowadaysusually filled with mineral wool and ceramic and further materials.However, this makes it impossible to make the exhaust mufflerrecyclable, since for it to be recycled, i.e. melted down, the mineralwool or ceramic constituents must first be removed from the interior ofthe exhaust muffler to enable the remainder to be completely melteddown.

In view of the solutions to an exhaust-gas treatment device which areshown in the prior art and the drawbacks which have been demonstrated inmuffler configurations which have been disclosed hitherto, the inventionis based on the object of considerably simplifying the production of asystem for exhaust-gas treatment, whether this be a muffler system or aparticle filter system, or in exhaust-gas catalytic converters forpurifying exhaust-gas streams, and of improving the recyclabilitythereof.

According to the invention, this object is achieved through the factthat, in a device for treating exhaust gases which is arranged in theexhaust-gas stream from an internal combustion engine and which has afeed-line connection stub and a discharge-line connection stub, both ofwhich are held on a housing which contains a filter material which hasat least one fabric layer made from metal wires or metal fibers, fordiversion, for retention of particulates contained in the exhaust gasand for muffling, shaped bodies are incorporated in the housing, whichshaped bodies, made from metallic fiber material, fill the empty spacesin the housing of the device for the treatment of exhaust gases.

The advantages which can be achieved with the solution which is proposedin accordance with the invention are considered to reside in particularin the fact that the shaped bodies which are provided inside the housingof the device for treating the exhaust-gas streams can be designed withsimple means and have huge flexibility in terms of their geometries. Byway of example, the shaped bodies may be configured in such a way thatthey pass through the housing of the particle filter or of theexhaust-gas catalytic converter or of the muffler in the axialdirection, i.e. parallel to the direction of flow of the exhaust-gasstreams to be treated, can be arranged so as to wind helically throughthe interior of the housing, but can also pass through the housing inmeandering form, so that the exhaust-gas stream can be forced to cover along path through the housing. In addition, other exhaust-gas streamconfigurations which lengthen the path of the gas stream passing throughthe housing are also conceivable. In addition, this type ofconfiguration of a muffler system, a catalytic converter system or aparticle filter system is also significantly more favorable in terms ofits intrinsic weight than a comparable structure using perforated orunperforated metal sheets. The metallic composite material used mayconsist of stainless steel wool or other metal fibers with a largesurface area which are incorporated in a woven mesh which serves assupport material. As a result, all individual shaped parts made frommetal sheets and by separate installation in the interior of the housingof the catalytic converter, muffler or particle filter system can bedispensed with.

In an advantageous configuration of the device which is proposed inaccordance with the invention, the metallic composite material consistsof a woven mesh which functions as a support material and metallicfibers which are introduced into it. The metallic fibers offer theadvantage of dissipating the heat which is carried in the incomingexhaust-gas stream as quickly as possible and have a large surface area,which is favorable with a view to particulate retention when used in aparticle filter system.

The shaped bodies which consist of the metallic composite material andare incorporated in the interior of the housing are extremely flexibleto produce, production being particularly simple. The shaped bodies, ifthey consist exclusively of metallic base material, have a porositywhich can be adjusted according to the way in which they are produced.The porosity has a decisive influence on the rate of flow of the exhaustgas through the muffler or particle filter which is configured inaccordance with the invention, and consequently the residence time ofthe exhaust-gas stream in the interior of a catalytic converter, aparticle filter or a muffler can be influenced by the way in which theindividual materials are pressed in the metallic composite materials.

According to an advantageous design variant of the device for treatingexhaust-gas streams which has been proposed in accordance with theinvention, shaped bodies for treating the gas streams which are fittedinto the interior of the housing can be arranged parallel to thedirection of flow of the exhaust-gas streams. It is possible to producethe various exhaust-gas flow paths through the interior of a device fortreating exhaust gas, whether this be a particle filter, a catalyticconverter for purifying exhaust gas or a muffler. It is irrelevantwhether it be one, two or more along, parallel to the axis of symmetryof a housing which is made in a round, oval or any other geometry. Inaddition to a coaxial extent of the shaped body made from metalliccomposite material, it is also readily possible to propose a meanderingextent of the shaped bodies made from metallic fiber material throughthe interior of the housing, with the result that the residence time ofthe exhaust gas guided in the shaped bodies in the interior of thehousing of the muffler, the catalytic converter or the particle filtercan be lengthened or influenced in a targeted way.

In addition to the coaxial forming of the shaped parts or an adjustablemeandering profile of the shaped parts in the interior of the housing,it is also possible to provide a shape-part geometry which is configuredhelically—in the form of a coil spring—and which runs in the interior ofthe housing at a short distance from the outer shell of this housing.The lengthening of the shaped parts, i.e. an increase in the pathlength, forces the exhaust gas to cover a longer distance through theinterior of the housing, with the result that, first of all, itsresidence time in the interior of the housing can be adjusted andthereby the particulate retention can be improved and, secondly, agreater dissipation of heat to the outer surface of the housing can beestablished.

In a further configuration of the device which is proposed in accordancewith the invention, metallic fiber material is enclosed in the emptyspaces, i.e. the spaces in the interior of the housing which do not holdshaped parts made from metallic composite material. In this way, it ispossible to produce a low-vibration bearing of the shaped parts madefrom metallic composite material, and also uniform heating or heatdistribution in the interior of the housing. In an advantageous designoption for the device which is proposed in accordance with theinvention, whether this be a particle filter, a muffler or anexhaust-gas catalytic converter for use in the automotive sector, theproportion of stainless steel material in the metallic compositematerial can be significantly higher in the region of the inlet end facefor entry to the housing than the stainless-steel proportion arranged onthe outlet side of the housing, in order for heat to be dissipated fromthe incoming exhaust-gas stream.

The device for treating gas streams can be used both in the mufflersystem, whether this be the main muffler or the front muffler, in themotor vehicle as a particle filter element for retaining soot particlesin commercial vehicles or in passenger automobiles, and furthermore aconfiguration which is proposed in accordance with the invention fortreatment of exhaust gas can also be used as a catalytic converter forpurifying exhaust gases from internal combustion engines. Furthermore,the solution according to the invention can also be used in stationarycombustion installations used in the industrial and domestic sectors.

In the configuration whereby the device which is proposed in accordancewith the invention is used for the retention of particulates, i.e. as aparticle filter, the particulate retention, i.e. the efficiency of thecleaning of the exhaust-gas stream, can be significantly increased as aresult of, firstly, a long residence time, i.e. a long path lengththrough the interior of the housing, being imposed upon on the incomingparticle-laden exhaust-gas stream from an air-compressing internalcombustion engine. Furthermore, if, in the case of particle filters, aconsiderable degree of pressing or knitting-together of the two metalliccomposite materials is established during production of the metalliccomposite material, a porosity which significantly improves theretention of particulates from the exhaust-gas stream is established inthe metallic composite material which virtually completely fills theinterior of the housing.

The invention is described in more detail with reference to the drawing,in which:

FIG. 1 shows a cross section through a partially open housing of adevice for treating exhaust gases, with shaped bodies diagrammaticallydepicted therein, and

FIG. 2 shows an axially extending shaped body of simpler geometry madefrom metallic composite material.

The illustration shown FIG. 1 shows a device for treating an exhaust-gasstream, for example a muffler device at internal combustion engines, indiagrammatic form.

It can be seen from the illustration presented in FIG. 1 that anincoming exhaust-gas stream 1 from an internal combustion engine,whether this be a gasoline-burning internal combustion engine or anair-compressing internal combustion engine, enters the interior of ahousing 6 of a device for treating the exhaust-gas stream 1 through aninlet connection stub 3.

In the configuration shown in FIG. 1, the stub diameter 5 substantiallycorresponds to the diameter of the shaped body 8 which is incorporatedin the interior of the housing 6, consists of a metallic compositematerial 19 and two of which are shown in the illustration presented inFIG. 1, extending substantially parallel to the axis of symmetry of thehousing 6. The inlet connection stub 3 is secured to the outer side 7.1of an inlet end side 7 of the housing 6 of the device for treating theexhaust-gas stream. The inlet connection stub opens out, through anopening, directly into the shaped body 8 which is provided in theinterior of the housing 6 and passes through the first empty space 11and further empty spaces 16 and 17.

On the outlet side of the housing 6 there is an outlet connection stub2, which is secured to the outer side 14.1 of the outlet end side 14 andwhich is designed in a similar way to the inlet connection stub 3 interms of stub diameter 5, substantially corresponding to the externaldiameter 15 of the shaped body made from metallic composite material 19.A correspondingly treated exhaust-gas stream 2 leaves the interior ofthe housing 6 through the outlet connection stub 2. The housing 6 may bepart of a muffler installation, or alternatively an installation forpurifying the exhaust gases, whether this be a particle filter or anexhaust-gas catalytic converter as is nowadays used in the automotiveindustry.

In addition to the end faces 7 and 14, the housing 6 comprises an outershell 13 which extends cylindrically around the end sides 7 and 14.Between the end sides 7, 14, individual empty spaces 11, 16 and 17 areformed in the interior of the housing 6, divided up by wall elements 12,18. The abovementioned empty spaces in the interior of the housing 6 arefilled with filler material, which is metallic fiber material, in orderto improve the muffling, for example in muffler systems, and the heatconduction for hot incoming exhaust-gas streams 1.

In the illustration shown in FIG. 1, the shaped bodies 8, of which twoare illustrated by way of example, are shown running substantiallycoaxially with respect to the geometry line of the housing 6. Comparedto the upper shaped body 8 accommodated in the housing 6, which is heldsubstantially coaxially with respect to the inlet and outlet connectionstubs 3, 4, a further shaped body 8, which is only represented inbroken-away form, is located parallel to the shaped body 8 whichconnects the connection stubs 3 and 4 to one another, in the interior ofthe housing 6. In addition to the geometry of the shaped bodies 8 whichis illustrated here, these shaped bodies may also adopt a meanderingpath through the interior of the housing 6, in order to impose a longerpath length through the interior of the housing 6 to the incomingexhaust-gas stream 1 and to increase its residence time in the interiorof the housing 6. A longer residence time in the interior of the housing6 of the device for treating exhaust-gas streams allows the temperatureof the incoming exhaust-gas stream 1 to be reduced further and allows animproved retention result in particle filter arrangements with regard tothe retention rate of the soot particles contained in the exhaust gasfrom an air-compressing internal combustion engine.

In addition to the shaped bodies being guided in meandering form throughthe interior of the housing 6, they can also be led through the interiorof the housing 6 in the manner of a coil spring in individual turnsrunning along the outer shell 13 of the housing 6. This has theadvantage that, in addition to good heat transfer to the outer surfaceof the housing 6, the longest possible residence time in the interior ofthe housing 6 is imparted to the incoming exhaust-gas stream 1, which inthe case of an air-compressing internal combustion engine has theassociated positive effect that the particulates contained in theexhaust gas can be filtered out as fully as possible.

In the exemplary embodiment illustrated in FIG. 1, the shaped bodies 8are illustrated passing through the individual walls 12, 18 in theregion of openings 20 and 21, respectively. The shaped bodies 8 consistof metallic fiber composite material comprising the components 19.1 and19.2. Reference numeral 19.1 denotes the woven mesh, which functions asa support material and the meshes of which may be of different sizes andmay adopt any desired geometries and may have a metallic fiber material,for example stainless steel wool, incorporated in them. The shapedbodies 8, which are in this case configured in rod form, are in eachcase surrounded on their outer surfaces 9 by filler material, which ispreferably metallic fiber material. Therefore, the interior of thehousing 6 consists entirely of metallic material, which has a favorableeffect on its recyclability, since there is now no need to separatedifferent materials, such as for example ceramic, glass fibers, mineralwool, when the device for treating exhaust-gas streams which isconfigured in accordance with the invention is being reused. It is nowpossible to dispense with separate disposal of mineral or glass woolwhich was incorporated in the empty spaces 11, 16, 17 as fillermaterials in previous configurations; this has a beneficial effect onthe recyclability of the device which is proposed in accordance with theinvention, whether it is used a as muffler, as a particle filter or asan exhaust-gas catalytic converter.

It can be seen from the illustration presented in FIG. 1 that the shapedparts 8, which can easily be produced in very complex geometries, arearranged at a distance, which is denoted by reference symbol 23, fromone another in the interior of the housing 6. The individual shapedparts in the interior of the housing 6, surrounded by the outer surface13, can be arranged at a greater distance 24 from this outer surface.The quantity of filler material, which is preferably metallic fibermaterial, which is to be arranged in this region is determined by thedistance 24 between the outer surface of the shaped bodies 8 made frommetallic composite material 19 and the inner wall of the outer shell 13of the housing 6. The heat transfer from the exhaust gas flowing throughthe shaped bodies 8 to the outer side of the lateral surface 13 of thehousing 6 can be influenced in this way. In addition to the flow of theincoming exhaust-gas stream 1 being guided in meandering or helical formthrough the shaped bodies 8, which are made from metallic compositematerial 19 and have extremely complex geometries, the heat transferfrom the incoming exhaust-gas stream 1 to the lateral surface 13 of thehousing 6 can also be predetermined by the shaped bodies made frommetallic composite material being spaced apart at a spacing 24 which canbe preselected.

In order to take account of the high temperatures at which the incomingexhaust-gas stream 1 enters the interior of the housing 6 through theinlet connection stub 3, there may be a high stainless steel content inthe region of the inlet-side end face 7 and in the shaped bodies 8,which consist of metallic composite material 19, and filler materialssurrounding them in the first empty space 11, which ensures betterdissipation of heat. The proportion of stainless steel in the metalliccomposite material may be lower at the outlet-side end face 14 of thehousing 6, since the outlet temperature of gas stream 2 emerging fromthe interior of the housing 6 of the device for treating exhaust-gasstreams is generally lower than the inlet temperature of the incoming,as yet untreated exhaust-gas stream 1. Although it has been illustratedon the basis of a muffler for exhaust-gas streams, the structure of acatalytic converter for purifying exhaust gases or the structure of aparticle filter for filtering out particulates is also constructed in asimilar manner to the muffler sketched in FIG. 1.

The illustration shown in FIG. 2 presents a shaped-body component 8,which is only diagrammatically depicted in the figure, in more detail.

The shaped-body component 8 consists of metallic composite material 19which is pressed or knitted together, and the porosity of which can inthis way be influenced in terms of the ability of exhaust-gas streams topass through it. The composite material 19 firstly includes a woven mesh19.1 which serves as a support fabric and may have a mesh width and anydesired mesh geometry, be they round, polygonal, diamond-shaped or thelike. Metallic fibers 19.2 which, by way of example, may be melted orproduced by chip-forming routes, are incorporated in the individualmeshes present in the support material 19.1. The two materials 19.1 and19.2 can be pressed or knitted together or joined to one another in anyother conceivable way, so that a composite material is produced. Theparticulate retention rate, for example the retention rate for sootparticles from the exhaust gas from air-compressing internal combustionengines, can be positively influenced according to the porosity, whichis established by the degree of pressing or knitting-together of themetallic composite materials 19.1 and 19.2. If, during filtering, theresidence time is selected by means of a helical or meandering guidanceof the exhaust-gas flow through the interior of the housing 6 and theporosity in the shaped body 8 is selected favorably, it is possible toachieve a significant particulate retention rate in the exhaust-gasstream from an air-compressing internal combustion engine (not shownhere) using a particle filter, or exhaust-gas catalytic converter, ofthis type consisting of purely metallic material. In addition, aparticle filter system or catalytic converter system of this type can bedisposed of very easily, since it consists exclusively of metallicmaterials and can therefore easily be melted down. With a particlefilter of this type, it is not necessary to separate differentmaterials, such as glass wool, mineral wool or ceramic materials. Evenwhen the device which is proposed in accordance with the invention fortreating exhaust gas is used as a particle filter or an exhaust-gascatalytic converter, it is possible to implement a stainless-steelmaterial distribution in the interior of the housing which takes accountof the temperature profile of the incoming exhaust-gas stream 1. Forexample, even with particle filters or catalytic converters, it ispossible to provide a higher stainless steel content, in order toimprove the conduction of heat, in the region of the empty spaces 11which lie closest to the inlet-side end side 7 of the housing 8 than atthe outlet-side end side 14 at the housing 6 of the device for treatingexhaust-gas streams 1. The remaining empty spaces 11, 16 and 17 of thehousing can be filled, for example, with stainless steel wool, sincethis material, unlike the abovementioned glass wool or mineral woolmaterials, can be recycled and there is no need for separationoperations.

The illustration presented in FIG. 2, which illustrates the direction offlow through the shaped body 8 by means of the incoming exhaust-gasstream 1 and the emerging, treated exhaust-gas stream 2, takes place viathe cross-sectional area 15, which in the exemplary embodimentillustrated in FIG. 2 is of approximately circular configuration. Theporosity which is predetermined by the production of the shaped body 8and leads to the favorable results with regard to the retention of sootparticles in the exhaust gas from air-compressing internal combustionengines is established in the inner region 10 of the shaped body 8consisting of metallic composite material 19.

Although this is not illustrated in FIG. 2, the outer lateral surface 9of the shaped body 8 is surrounded by filler material, which is likewisemetallic composite material 19 and which is accommodated in the emptyspaces 11, 16, 17 (cf. FIG. 1) of the housing 6 of the device fortreating exhaust-gas streams for muffling purposes. In addition to themuffling action, the filler material 19 also makes it possible toimprove the conduction of heat and the heat transfer from the hotexhaust-gas streams which are present on the inlet side to the outerlateral surface 13 of the housing 6.

The configuration of a device for treating exhaust gas which is proposedin accordance with the invention enables this device, in the form of apot-like housing, to be made completely from metal, which improves itsrecyclability and obviates the need for separation operations toseparate different materials. The intrinsic weight of the configurationof a device for treating exhaust-gas streams which is proposed inaccordance with the invention is significantly reduced compared to theconventional skeleton structures comprising perforated metal sheets andtubes, and furthermore the labor-intensive and cost-intensive skeletonstructure as has hitherto been customary in mufflers, particle filtersor exhaust-gas catalytic converters can then be dispensed withaltogether. It is now also possible to completely dispense with holdingstocks of a very wide range of different perforated metal sheetconfigurations for model-specific muffler configurations for motorvehicles.

List of reference symbols 1 Incoming exhaust-gas stream 2 Emergingexhaust-gas stream 3 Inlet connection stub 4 Outlet connection stub 5Connection stub diameter 6 Housing 7 Inlet end side 7.1 Outer side 7.2Inner side 8 Shaped body 9 Outer shell 10 Inner region 11 Empty space 12Wall 13 Lateral surface 14 Outlet end side 14.1 Outer side 14.2 Innerside 15 Shaped body cross section 16 Empty space 17 Empty space 18 Wall19 Metallic composite material 19.1 Support fabric 19.2 Support fabric +metal fibers 20 Passage opening in wall 12 21 Passage opening in wall 1822 Shaped body length 23 Spacing 24 Lateral surface spacing 25 Passagearea 26 Wall thickness 27 Filler material for empty spaces 11, 16, 17

1. A device for treating exhaust gases (1) which is arranged in theexhaust-gas stream from an internal combustion engine or in theexhaust-gas line from stationary combustion installations and which hasa feed-line connection stub (3) and a discharge-line connection stub(4), which are held on a housing (6) which contains a filter material(19) which has at least one fabric layer made from metal wires or metalfibers, characterized in that for diversion, particulate retention andmuffling purposes there are shaped bodies (8) in the housing (6), whichconsist of metallic fiber composite (19.1, 19.2) as composite material,the empty spaces (11, 16, 17) in the housing (6) being filled withmetallic fiber material, wherein in a region of an inlet end face (7) ofthe housing (6) the proportion of stainless steel material (19.2) in thecomposite material (19) is higher than at the outlet-side boundary (14)of the housing (6), in order to conduct heat out of the incomingexhaust-gas stream (1).
 2. The device as claimed in claim 1,characterized in that the composite material (19) comprises a woven mesh(19.1), which serves as a support fabric, and metallic fibers (19.2)which are introduced into this woven mesh.
 3. The device as claimed inclaim 1, characterized in that the shaped bodies (8) which areincorporated in the interior of the housing (6) for treating the gasstreams (1, 2) are arranged parallel to the direction of flow of theexhaust-gas streams (1, 2).
 4. The device as claimed in claim 1,characterized in that the shaped bodies (8) adopt a meandering paththrough the interior of the housing (6).
 5. The device as claimed inclaim 1, characterized in that the shaped bodies (8) are arranged so asto run helically through the interior of the housing (6).
 6. The deviceas claimed in claim 1, characterized in that the empty spaces (11, 16,17) in the housing (6) are filled with metallic fiber material as fillermaterial.
 7. The device as claimed in claim 1, characterized in that itis used as a main and/or front muffler in an exhaust system.
 8. Thedevice as claimed in claim 1, characterized in that it is provided as aparticle filter for retaining particulates from the exhaust-gas stream(1) which enters it.
 9. The device as claimed in claim 8, characterizedin that the retention of particulates by the shaped bodies (8) can beinfluenced by their longitudinal extent (22), their passage surface area(25) and the by the porosity of the metallic composite material (19) ofthe bodies (8).
 10. The device as claimed in claim 1, characterized inthat it is used as an exhaust-gas catalytic converter for purifyingexhaust-gas streams.
 11. The device as claimed in claim 1 wherein theentire housing is made of metallic material.